HARVEY, Ill. (AP) — Cook County Sheriff Tom Dart says the last four hostages have been released unharmed to end a standoff with two armed men in a southern Chicago suburb.

Dart says the two adults and two children still being held were freed Wednesday morning without a shot being fired. He says two suspects have been arrested.

The standoff began about 21 hours earlier when police in the small city responded to a neighbor's report of a possible burglary at the home.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

Negotiators worked late into the night in an effort to persuade two men barricaded in a home in the southern Chicago suburb of Harvey to end their standoff with police and release the last of six children and two adults they took hostage.

Four of the children had been released after hours of talks between the suspects and hostage negotiators.

Authorities say the two men took the captives after Harvey police responded to a call of a burglary in progress at a home about 12:50 p.m. Tuesday. There was an exchange of gunfire that left two officers wounded.

Harvey spokesman Sean Howard said after the shooting, the two suspects ran into a nearby home, where they barricaded themselves.

Police had initially said five children and one adult were taken captive. However, Howard said one of the children released revealed to police that there were actually six children and two adults being held. Howard would not say whether the suspects know the hostages or whether the hostages are related.

Officers, including a SWAT team, surrounded the home and the entire block of homes was evacuated, affecting about 100 residents, Howard said. A nearby middle school was evacuated, but only staff members were in the building.

Howard said the first two children released appeared to be in good physical condition and were taken to a local hospital for observation. He said the third child, a 1-year-old, wasn't hospitalized. The fourth child was released nearly 11 hours after being taken hostage.

The first child has a breathing problem, Howard said. The men put the child on the front porch and a member of the SWAT team got the child.

"There have been no bumps in the road yet," Howard said of the negotiating effort. "We hope to get this resolved peacefully."

Howard told The Associated Press that authorities do not know the hostage-takers but have identified the hostages. He would not comment on the relationship between the hostages but said a woman hostage is believed to be a nurse. He did not identify the children who were released.

"Right now, we don't want to jeopardize the integrity of negotiation process," Howard said. "We want to protect those children as much as we can. The less information right now, the better."

Page 2 of 2 - Officer Darnell Keel, an 18-year veteran of the police force, was in stable condition at a hospital with a broken arm after the exchange of gunfire and will have surgery, Howard said. A second officer suffered a graze wound to an arm.

Twenty-six law enforcement agencies were assisting, Howard said. An armored vehicle and officers in body armor with high-powered rifles were seen in the neighborhood. The state police SWAT team responded, said Illinois State Police spokeswoman Monique Bond.